Method for adiabatic cooling type crystallization of organic compound and apparatus therefor

Abstract

A method including carrying out adiabatic cooling and evaporation operation of a coolant in a crystallizer ( 20 ) for a mixture solution of a target organic compound containing the coolant; taking out crystal slurry produced by the operation from the crystallizer ( 20 ); pressurizing evaporated vapor to a pressure higher than the operation pressure in the crystallizer ( 20 ) by a compressor ( 30 ) and then introducing the vapor to an absorption condenser ( 10 ); cooling for condensation the mixture solution of organic compound and the evaporated vapor that has been pressurized while allowing them to contact each other in the absorption condenser ( 10 ); introducing the crystal slurry taken out of the crystallizer ( 20 ) to a purification means ( 70 ) for purification of the crystal; and introducing a clarified liquid in the purification means ( 70 ) to at least one of the crystallizer ( 20 ) and the absorption condenser ( 10 ).

1. A method for adiabatic cooling type crystallization of organic compound comprising: introducing a mixture solution containing a target organic compound along with coolant condensate into a crystallizer, and performing evaporation operation to the coolant within the crystallizer so as to execute adiabatic cooling by the evaporation operation, thus carrying out crystallization operation of the target organic compound;
 taking out organic compound crystal slurry, which is produced by the crystallization operation, from the crystallizer; 
 pressurizing the evaporated coolant vapor, which is obtained from the evaporation operation of the coolant vapor, to a pressure higher than operation pressure in the crystallizer by a compressor and then introducing the pressurized evaporated coolant vapor to an absorption condenser; 
 cooling, by a cooling column through which cooling water passes, the pressurized evaporated coolant vapor and the mixture solution, while allowing the pressurized evaporated coolant vapor and the mixture solution to contact each other, thus allowing the mixture solution to be subjected to absorption and condensation of the pressurized coolant vapor; and 
 introducing the crystal slurry taken out of the crystallizer to a purification means to purify the crystal, and introducing a clarified liquid in the purification means to at least one of the crystallizer and the absorption condenser as it is, and 
 wherein the purification means is an vertical melt purification column having a clarified liquid discharge means in the lower portion and a heating means in the upper portion, to-the crystal slurry taken out of the crystallizer being introduced into the purification means, and in the purification column, the crystal moving to the upper portion is molten by the heating means in the upper portion, part of the molten matter or the molten liquid containing the crystal is taken out for making a product, the other portion is allowed to fall, as a reflux liquid, through a crystal group that is rising, the mother liquid is washed out with the reflux liquid, the purified crystal is allowed to move upward, and the clarified liquid having reached the clarified liquid discharge means in the lower portion is introduced to the absorption condenser as it is. 
 
     
     
       2. The method for adiabatic cooling type crystallization of organic compound according to  claim 1 , wherein the crystal slurry taken out of the crystallizer is introduced to the purification means after being concentrated by a concentration means. 
     
     
       3. The method for adiabatic cooling type crystallization of organic compound according to  claim 1 , wherein the clarified liquid in a clarified portion in the crystallizer is introduced to the absorption condenser. 
     
     
       4. The method for adiabatic cooling type crystallization of organic compound according to  claim 1 , wherein the operation pressure in the crystallizer is around normal atmospheric pressure or equal to or lower than four atmospheric pressure, and the evaporated coolant vapor, which is obtained from the evaporation operation of the coolant vapor, is pressurized to a pressure which is higher than operation pressure in the crystallizer and equal to or lower than eight atmospheric pressure. 
     
     
       5. The method for adiabatic cooling type crystallization of organic compound according to  claim 1 , wherein the concentration of the coolant in the absorption condensate from the absorption condenser is set to from 1 to 70%. 
     
     
       6. The method for adiabatic cooling type crystallization of organic compound according to  claim 1 , wherein the mixture solution of organic compound is a xylene mixture containing paraxylene and the coolant vapor is propane. 
     
     
       7. The method for adiabatic cooling type crystallization of organic compound according to  claim 2 , wherein the coolant dissolved in a discharged liquid discharged by the concentration means to outside of a system is recovered and supplied as make-up to a suction means of the compressor.